Acne is a common multifaceted skin disorder of the hair follicles and sebaceous glands which leads to the formation of comedones. It affects nearly all adolescents and may also persist into adulthood. Adult women may particularly be affected and experience premenstrual outbreaks.
Genetic predisposition, overproduction of sebum (seborrhea), androgens, follicular keratinization disorders (comedogenesis) and bacterial colonization accompanied by inflammatory factors are various factors which play a determining role in the formation of acne.
Several forms of acne exist, the factor common to all of them being the attack of pilosebaceous follicles. For example, mention may be made of acne conglobata, acne keloidalis nuchae, drug-induced acne, recurrent acne miliaris, acne necrotica, acne neonatorum, premenstrual acne, occupational acne, senile acne, solar acne and acne vulgaris.
Acne vulgaris, also known as polymorphous juvenile acne, is the most common and comprises four stages:                stage 1 corresponds to comedonal acne and is characterized by a large number of microcysts and open and/or closed comedones;        stage 2, or papulopustular acne, is mildly to moderately serious and is characterized by the presence of microcysts and open and/or closed comedones, but also red papules and pustules. It affects mainly the face and leaves some scars;        stage 3, or papulocomedonal acne, is more serious and extends to the back, thorax and shoulders. It is accompanied by a large number of scars;        stage 4, or nodulocystic acne, is accompanied by numerous scars. It exhibits nodules and also large, painful purplish pustules.        
These various forms of acne are traditionally treated by using various active agents. For example, mention may be made of anti-seborrheic and anti-infective agents such as benzoyl peroxide marketed by Pierre Fabre under the name Eclaran®. Mention may also be made of retinoids such as tretinoin, marketed by Galderma under the name Retacnyl®, or isotretinoin, marketed by Roche Laboratories under the name Roaccutane®, for their capacity to act on keratinocyte proliferation and differentiation. Naphthoic acid derivatives, such as adapalene, described notably in the application FR 2 837 101, or the derivatives thereof, described in the patent EP 0 850 909, are also recognized as active substances for treating acne.
However, the use of these active agents, notably retinoids, causes numerous side effects in patients. In particular, retinoid-based treatments may cause dry skin, irritation, erythema, desquamation and stinging or burning in treated patients. Thus, the use of such treatments also requires the application of multiple moisturizing, humectant and soothing agents to provide relief to the patient.
Moreover, these various treatments are often combined with a course of antibiotics such as tetracycline, erythromycin, minocycline and doxycycline to treat acneic lesions, but their low lipid solubility requires regular and frequent administration which may generate resistance phenomena and promote the development of these resistant organisms as well as intolerance-related problems in the patient.
Thus, it must be acknowledged that there exists a need to provide acne treatments that are more effective and that do not cause side effects in the patient. In particular, there is to date no treatment that acts on both the factors involved in acne formation and the inflammatory reactions resulting therefrom.